SIST-TS ISO/TS 22028-3:2011
Photography and graphic technology - Extended colour encodings for digital image storage, manipulation and interchange - Part 3: Reference input medium metric RGB colour image encoding (RIMM RGB)
Photography and graphic technology - Extended colour encodings for digital image storage, manipulation and interchange - Part 3: Reference input medium metric RGB colour image encoding (RIMM RGB)
This part of ISO 22028 specifies a family of scene-referred extended colour gamut RGB colour image encodings designated as Reference input medium metric RGB (RIMM RGB). Digital images encoded using RIMM RGB can be manipulated, stored, transmitted, displayed, or printed by digital still picture imaging systems. Three precision levels are defined using 8-, 12- and 16-bits/channel. An extended luminance dynamic range version of RIMM RGB is also defined designated as Extended reference input medium metric RGB (ERIMM RGB). Two precision levels of ERIMM RGB are defined using 12- and 16-bits/channel.
Photographie et technologie graphique - Codages par couleurs étendues pour stockage, manipulation et échange d'image numérique - Partie 3: Codage d'image en couleurs RVB par référence d'entrée par voie métrique
Fotografija in grafična tehnologija - Razširjeno barvno kodiranje za shranjevanje, ravnanje in izmenjavo digitalnih slik - 3. del: Referenčna vhodna medijska metrika RGB barvnega kodiranja slik (RIMM RGB)
Ta del ISO 22028 določa družino s scensko razširjeno barvno paleto RGB barvnega kodiranja slik, označeno kot referenčna vhodna medijska metrika (RIMM RGB). Digitalne slike, kodirane z RIMM RGB, se lahko upravljajo, shranjujejo, pošiljajo, prikazujejo ali tiskajo z digitalnimi upodobitvenimi sistemi za mirujoče slike. Opredeljene so tri ravni natančnosti z uporabo 8, 12 in 16 bitov/kanal. Opredeljena je tudi razširjena različica dinamičnega obsega svetilnosti RIMM RGB, označena kot razširjena referenčna vhodna medijska metrika RGB (ERIMM RGB). Opredeljeni sta dve ravni natančnosti ERIM RGB z uporabo 12 in 16 bitov/kanal.
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TECHNICAL ISO/TS
SPECIFICATION 22028-3
First edition
2006-08-15
Photography and graphic technology —
Extended colour encodings for digital
image storage, manipulation and
interchange —
Part 3:
Reference input medium metric RGB
colour image encoding (RIMM RGB)
Photographie et technologie graphique — Codages par couleurs
étendues pour stockage, manipulation et échange d'image
numérique —
Partie 3: Codage d'image en couleurs RVB par référence d'entrée par
voie métrique
Reference number
ISO/TS 22028-3:2006(E)
©
ISO 2006
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ISO/TS 22028-3:2006(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.
© ISO 2006
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2006 – All rights reserved
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ISO/TS 22028-3:2006(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 1
4 Requirements . 5
4.1 General. 5
4.2 Reference viewing environment. 6
4.3 Reference medium primaries and white point. 7
4.4 RIMM RGB colour image encoding. 7
4.5 Inverse RIMM RGB transformation . 11
Annex A (informative) Example colour rendering transform from RIMM RGB to ROMM RGB. 14
Bibliography . 18
© ISO 2006 – All rights reserved iii
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ISO/TS 22028-3:2006(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
In other circumstances, particularly when there is an urgent market requirement for such documents, a
technical committee may decide to publish other types of normative document:
⎯ an ISO Publicly Available Specification (ISO/PAS) represents an agreement between technical experts in
an ISO working group and is accepted for publication if it is approved by more than 50 % of the members
of the parent committee casting a vote;
⎯ an ISO Technical Specification (ISO/TS) represents an agreement between the members of a technical
committee and is accepted for publication if it is approved by 2/3 of the members of the committee casting
a vote.
An ISO/PAS or ISO/TS is reviewed after three years in order to decide whether it will be confirmed for a
further three years, revised to become an International Standard, or withdrawn. If the ISO/PAS or ISO/TS is
confirmed, it is reviewed again after a further three years, at which time it must either be transformed into an
International Standard or be withdrawn.
ISO/TS 22028-3 was prepared by Technical Committee ISO/TC 42, Photography, in collaboration with
Technical Committee ISO/TC 130, Graphic technology.
ISO 22028 consists of the following parts, under the general title Photography and graphic technology —
Extended colour encodings for digital image storage, manipulation and interchange:
⎯ Part 1: Architecture and requirements
⎯ Part 2: Reference output medium metric RGB colour image encoding (ROMM RGB)
[Technical Specification]
⎯ Part 3: Reference input medium metric RGB colour image encoding (RIMM RGB)
[Technical Specification]
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ISO/TS 22028-3:2006(E)
Introduction
This part of ISO 22028 has been developed in order to meet the industry need for a complete,
fully-documented, publicly-available definition of a wide-primary scene-referred extended colour gamut
red-green-blue (RGB) colour image encoding. This encoding provides a way to represent scene-referred
images that does not limit the colour gamut to those colours capable of being displayed on a CRT monitor, or
require the use of negative RGB colorimetry co-ordinates.
A scene-referred extended colour gamut colour encoding is particularly desirable for professional photography
applications. For example, colours captured by digital cameras, as well as conventional capture devices such
as photographic film, can be outside those that can be represented within the colour gamut of a typical
monitor or other types of output devices. Similarly, scene-referred images can have a larger luminance
dynamic range than output-referred images since they have not been modified by a colour rendering process
to fit the images to a specific output medium applying appropriate tone and colour reproduction aims.
Retaining the unrendered scene-referred image data has the advantage that it preserves the option to make
decisions about how a particular image is to be rendered. For example, a scene-referred image of a backlit
scene can retain information about both the dark foreground region and the bright background region of the
scene. This information can be used to make a properly exposed print of either the foreground region or the
background region, or alternatively can be used to create an improved image by rendering the two regions
differently.
By using a standard scene-referred extended colour gamut colour image encoding, images can be stored,
interchanged and manipulated without restricting the image to a particular rendering intent or output device.
The Reference input medium metric RGB (RIMM RGB) colour encoding specified in this part of ISO 22028
meets the needs of these types of applications. An extended dynamic range version of this colour image
encoding known as Extended reference input medium metric RGB (ERIMM RGB) is also specified for use with
high-dynamic range input sources. (E)RIMM RGB is intended to be a companion to the output-referred ROMM
RGB colour image encoding specified in ISO/TS 22028-2. Both colour encodings are based on the same
“wide RGB” additive colour space to facilitate the development of image processing algorithms and simple
colour rendering transformations to convert scene-referred RIMM RGB images to rendered output-referred
ROMM RGB images.
The International Organization for Standardization (ISO) draws attention to the fact that it is claimed that
compliance with this document may involve the use of patents concerning extended range colour encodings
given in 4.4 and 4.5. ISO takes no position concerning the evidence, validity and scope of this patent right.
The holder of this patent right has assured the ISO that he/she is willing to negotiate licences under
reasonable and non-discriminatory terms and conditions with applicants throughout the world. In this respect,
the statement of the holder of this patent right is registered with ISO. Information may be obtained from
Director, Corporate Commercial Affairs
Eastman Kodak Company
343 State Street
Rochester, New York 14650-0211, U.S.A.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights other than those identified above. ISO shall not be held responsible for identifying any or all such patent
rights.
© ISO 2006 – All rights reserved v
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TECHNICAL SPECIFICATION ISO/TS 22028-3:2006(E)
Photography and graphic technology — Extended colour
encodings for digital image storage, manipulation and
interchange —
Part 3:
Reference input medium metric RGB colour image encoding
(RIMM RGB)
1 Scope
This part of ISO 22028 specifies a family of scene-referred extended colour gamut RGB colour image
encodings designated as Reference input medium metric RGB (RIMM RGB). Digital images encoded using
RIMM RGB can be manipulated, stored, transmitted, displayed, or printed by digital still picture imaging
systems. Three precision levels are defined using 8-, 12- and 16-bits/channel. An extended luminance
dynamic range version of RIMM RGB is also defined designated as Extended reference input medium metric
RGB (ERIMM RGB). Two precision levels of ERIMM RGB are defined using 12- and 16-bits/channel.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 22028-1:2004, Photography and graphic technology — Extended colour encodings for digital image
storage, manipulation and interchange — Part 1:Architecture and requirements
ISO/CIE 10527:1991, CIE standard colorimetric observers
CIE Publication 15, Colorimetery
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
adapted white
colour stimulus that an observer who is adapted to the viewing environment would judge to be perfectly
achromatic and to have a luminance factor of unity; i.e. absolute colorimetric coordinates that an observer
would consider to be a perfect white diffuser
NOTE The adapted white can vary within a scene.
3.2
additive RGB colour space
colorimetric colour space having three colour primaries (generally red, green and blue) such that CIE XYZ
tristimulus values can be determined from the RGB colour space values by forming a weighted combination of
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ISO/TS 22028-3:2006(E)
the CIE XYZ tristimulus values for the individual colour primaries, where the weights are proportional to the
radiometrically linear colour space values for the corresponding colour primaries
NOTE 1 A simple linear 3 × 3 matrix transformation can be used to transform between CIE XYZ tristimulus values and
the radiometrically linear colour space values for an additive RGB colour space.
NOTE 2 Additive RGB colour spaces are defined by specifying the CIE chromaticity values for a set of additive RGB
primaries and a colour space white point, together with a colour component transfer function.
3.3
colorimetric colour space
colour space having an exact and simple relationship to CIE colorimetric values
NOTE Colorimetric colour spaces include those defined by CIE (e.g. CIE XYZ, CIELAB, CIELUV, etc.), as well as
colour spaces that are simple transformations of those colour spaces (e.g. additive RGB colour spaces).
3.4
colour component transfer function
single variable, monotonic mathematical function applied individually to one or more colour channels of a
colour space
NOTE 1 Colour component transfer functions are frequently used to account for the nonlinear response of a reference
device and/or to improve the visual uniformity of a colour space.
NOTE 2 Generally, colour component transfer functions will be nonlinear functions such as a power-law (i.e. “gamma”)
function or a logarithmic function. However, in some cases a linear colour component transfer function can be used.
3.5
colour encoding
generic term for a quantized digital encoding of a colour space, encompassing both colour space encodings
and colour image encodings
3.6
colour gamut
solid in a colour space, consisting of all those colours that are either: present in a specific scene, artwork,
photograph, photomechanical, or other reproduction; or capable of being created using a particular output
device and/or medium
3.7
colour image encoding
digital encoding of the colour values for a digital image, including the specification of a colour space encoding,
together with any information necessary to properly interpret the colour values such as the image state, the
intended image viewing environment and the reference medium
NOTE 1 In some cases; the intended image viewing environment will be explicitly defined for the colour image
encoding. In other cases, the intended image viewing environment can be specified on an image-by-image basis using
metadata associated with the digital image.
NOTE 2 Some colour image encodings will indicate particular reference medium characteristics, such as a reflection
print with a specified density range. In other cases; the reference medium will be not applicable, such as with a scene-
referred colour image encoding, or will be specified using image metadata.
NOTE 3 Colour image encodings are not limited to pictorial digital images that originate from an original scene, but are
also applicable to digital images with content such as text, line art, vector graphics and other forms of original artwork.
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ISO/TS 22028-3:2006(E)
3.8
colour rendering
mapping of image data representing the colour-space coordinates of the elements of a scene to output-
referred image data representing the colour space coordinates of the elements of a reproduction
NOTE Colour rendering generally consists of one or more of the following:
⎯ compensating for differences in the input and output viewing conditions;
⎯ tone scale and gamut mapping to map the scene colours onto the dynamic range and colour gamut of the
reproduction;
⎯ applying preference adjustments.
3.9
colour space
geometric representation of colours in space, usually of three dimensions
[CIE Publication 17.4:1987, 845-03-25]
3.10
colour space encoding
digital encoding of a colour space, including the specification of a digital encoding method, and a colour space
value range
NOTE Multiple colour space encodings can be defined based on a single colour space where the different colour
space encodings have different digital encoding methods and/or colour space value ranges. (For example, 8-bit sRGB and
10-bit e-sRGB are different colour space encodings based on a particular RGB colour space.)
3.11
colour space white point
colour stimulus to which colour space values are normalized
NOTE It is not necessary that the colour space white point correspond to the assumed adapted white point and/or the
reference medium white point for a colour image encoding.
3.12
continuous colour space values
real-valued, unbounded colour space values that have not been encoded using a digital encoding method
3.13
digital imaging system
system that records and/or produces images using digital data
3.14
extended gamut
colour gamut extending outside that of the standard sRGB CRT display as defined by IEC 61966-2-1
3.15
image state
attribute of a colour image encoding indicating the rendering state of the image data
NOTE The primary image states defined in this document are the scene-referred image state, the original-referred
image state and the output-referred image state.
3.16
luminance factor
ratio of the luminance of the surface element in the given direction to that of a perfect reflecting or transmitting
diffuser identically illuminated
[CIE Publication 17.4:1987, 845-04-69]
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ISO/TS 22028-3:2006(E)
3.17
observer adaptive luminance factor
ratio of the luminance of a stimulus to the luminance of a stimulus that an observer adapted to the viewing
environment would interpret to be a perfect white diffuser
3.18
output-referred image state
image state associated with image data that represents the colour space coordinates of the elements of an
image that has undergone colour rendering appropriate for a specified real or virtual output device and
viewing conditions
NOTE 1 When the phrase “output-referred” is used as a qualifier to an object, it implies that the object is in an output-
referred image state. For example, output-referred image data is image data in an output-referred image state.
NOTE 2 Output referred image data is referred to the specified output device and viewing conditions. A single scene
can be colour rendered to a variety of output-referred representations depending on the anticipated output viewing
conditions, media limitations, and/or artistic intents.
NOTE 3 Output-referred image data can become the starting point for a subsequent reproduction process. For
example, sRGB output-referred image data is frequently considered to be the starting point for the colour re-rendering
performed by a printer designed to receive sRGB image data.
3.19
scene
spectral radiances of a view of the natural world as measured from a specified vantage point in space and at a
specified time
NOTE A scene can correspond to an actual view of the natural world or to a computer-generated virtual scene
simulating such a view.
3.20
scene-referred image state
image state associated with image data that represents estimates of the colour space coordinates of the
elements of a scene
NOTE 1 When the phrase “scene-referred” is used as a qualifier to an object, it implies that the object is in a scene-
referred image state. For example, scene-referred image data is image data in a scene-referred image state.
NOTE 2 Scene-referred image data can be determined from raw DSC image data before colour rendering is performed.
Generally, DSCs do not write scene-referred image data in image files, but some do so in a special mode intended for this
purpose. Typically, DSCs write standard output-referred image data where colour rendering has already been performed.
NOTE 3 Scene-referred image data typically represents relative scene colorimetry estimates. Absolute scene
colorimetry estimates can be calculated using a scaling factor. The scaling factor can be derived from additional
information such as the image OECF, FNumber or ApertureValue, and ExposureTime or ShutterSpeedValue tags.
NOTE 4 Scene-referred image data can contain inaccuracies due to the dynamic range limitations of the capture
device, noise from various sources, quantization, optical blurring and flare that are not corrected for, and colour analysis
errors due to capture device metamerism. In some cases, these sources of inaccuracy can be significant.
NOTE 5 The transformation from raw DSC image data to scene-referred image data depends on the relative adopted
whites selected for the scene and the colour space used to encode the image data. If the chosen scene adopted white is
inappropriate, additional errors will be introduced into the scene-referred image data. These errors can be correctable if
the transformation used to produce the scene-referred image data is known, and the colour encoding used for the
incorrect scene-referred image data has adequate precision and dynamic range.
NOTE 6 The scene can correspond to an actual view of the natural world, or be a computer-generated virtual scene
simulating such a view. It can also correspond to a modified scene determined by applying modifications to an original
scene to produce some different desired scene. Any such scene modifications need to leave the image in a scene-referred
image state, and need to be done in the context of an expected colour rendering transform.
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ISO/TS 22028-3:2006(E)
3.21
tristimulus value
amounts of the three reference colour stimuli, in a given trichromatic system, required to match the colour of
the stimulus considered
[CIE Publication 17.4:1987, 845-03-22]
3.22
veiling glare
light, reflected from an imaging medium, that has not been modulated by the means used to produce the
image
NOTE 1 Veiling glare lightens and reduces the contrast of the darker parts of an image.
NOTE 2 In CIE Publication 122, the veiling glare of a CRT display is referred to as ambient flare.
3.23
viewing flare
veiling glare that is observed in a viewing environment but not accounted for in radiometric measurements
made using a prescribed measurement geometry
NOTE The viewing flare is expressed as a percentage of the luminance of adapted white.
4 Requirements
4.1 General
Reference input medium metric RGB (RIMM RGB) is an extended colour gamut RGB colour image encoding
of the colorimetry of a scene-referred image. The scene-referred image has the intended colour appearance
when viewed in a specified reference viewing environment. The image colorimetry is encoded in terms of an
additive RGB colour space associated with a hypothetical additive colour device having a specified set of
primaries, no cross-talk between the colour channels and a maximum luminance value corresponding to
200 % of a perfect diffuse reflector (i.e. an observer adaptive luminance factor of 2,0).
NOTE 1 Scene-referred image data can correspond to an actual view of the natural world, or a simulation of such a
view. It can also correspond to a modified scene determined by applying modifications to an original scene. For example,
such modifications could include removing haze from the captured image, or allowing a user to manually adjust the
exposure/white balance. It could also include more complex operations such as using a “dodge-and-burn” algorithm to
correct over-exposed regions of a backlit scene. (This can be viewed as being analogous to “re-lighting” the scene.) Scene
modifications could also include applying desired changes to the scene such as simulating a “night” scene, making grass
greener to make it look healthier, or making the sky bluer to make it look clearer. Any such scene modifications need to
leave the image in a scene-referred image state, and need to be done in the context of the expected colour rendering
transform. For example, typical colour rendering transforms will include a boost in the chroma of the image. Any boost in
colourfulness of the scene (e.g. making the grass greener) must be done with the knowledge that there will be an
additional chroma boost during colour rendering. Consequently, the colour rendering transform must be included in any
image preview path that is used to provide subjective feedback to a user during the scene-editing process.
NOTE 2 The image colorimetry of the scene-referred image can contain inaccuracies due to the dynamic range
limitations of the capture device, noise from various sources, quantization, optical blurring and flare that are not corrected
for, and colour analysis errors due to capture device metamerism. In some cases, these sources of inaccuracy can be
significant.
Three different precision levels are defined, and shall be identified as RIMM8 RGB, RIMM12 RGB and
RIMM16 RGB, for 8-, 12- and 16-bits/channel (24-, 36- and 48-bits/pixel) representations, respectively.
Extended reference input medium metric RGB (ERIMM RGB) is an extended luminance dynamic range
version of RIMM RGB having a maximum observer adaptive luminance factor of about 316. Two different
precision levels are defined, and shall be identified as ERIMM12 RGB and ERIMM16 RGB, for 12- and
16-bits/channel (36- and 48-bits/pixel) representations, respectively.
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ISO/TS 22028-3:2006(E)
The image colorimetry shall be based on flareless (or flare corrected) colorimetric measurements as described
in CIE Publication No. 15 using the CIE 1931 standard colorimetric observer defined in ISO/CIE 10527.
When digital images are interchanged in an open systems environment using the RIMM RGB or ERIMM RGB
colour encodings, a default colour rendering function or a full resolution standard output-referred image should
be associated with the RIMM RGB or ERIMM RGB image data in order to unambiguously define baseline
colour rendering aims for the image, and allow the image to be used in applications which do not directly
support the usage of scene-referred image data. Furthermore, in an open systems environment, the RIMM
RGB or ERIMM RGB image data should be exchanged using a file format which requires the file reader to
apply the default colour rendering function or use the standard output-referred image data as the image data
to be conveyed, unless the RIMM RGB or ERIMM RGB image data is specifically requested by the application.
NOTE 3 The JPEG 2000 file format provides a mechanism for storing images in RIMM RGB or ERIMM RGB and
specifying baseline colour rendering aims through the use of the Restricted ICC Profile method.
NOTE 4 In some cases, it can be desirable for a user or an application to override the provided baseline colour
rendering aims in order to specify custom colour rendering aims for an image.
The colour image encoding defined in this Technical Specification conforms to the requirements defined in
Clause 5 of ISO 22028-1:2004.
4.2 Reference viewing environment
The reference viewing environment shall be such that the adapted white has the chromaticity values of
CIE Standard Illuminant D (x = 0,345 7, y = 0,358 5).
50 0 0
The absolute luminance level of the adapted white in the reference viewing environment shall be
2
15 000 cd/m .
NOTE 1 This absolute luminance level is intended to be typical of bright outdoor viewing environments.
NOTE 2 The luminance of the adapting field can be assumed to be 20 % of the luminance of the adapted white.
The reference viewing environment shall be characterized by an average surround. This means that the area
immediately surrounding the image border shall be assumed to be a uniform grey having the chromaticity
values of CIE standard illuminant D (x = 0,345 7, y = 0,358 5) and an observer adaptive luminance factor
50 0 0
of 0,2 relative to the adapted white.
There is no viewing flare for the scene other than that already included in the scene colorimetric values.
NOTE 3 The reference viewing environment is intended to provide a context for interpreting the colour appearance of
the encoded image colorimetry. It does not necessarily correspond to the original viewing environment for the
scene-referred image data. In many cases, it can be desirable to interpret the actual relative colorimetry of the image in
the context of the reference viewing environment, even when the image is captured in a different viewing environment.
(A chromatic adaptation and/or white balance step is usually required to ensure that neutral image content is properly
reproduced.) For example, if an image is captured in a dim viewing environment, it is often pleasing to define the desired
colour appearance of the image relative to the brighter reference viewing environment resulting in higher perceived
luminance and chrominance c
...
SLOVENSKI STANDARD
SIST-TS ISO/TS 22028-3:2011
01-julij-2011
)RWRJUDILMDLQJUDILþQDWHKQRORJLMD5D]ãLUMHQREDUYQRNRGLUDQMH]DVKUDQMHYDQMH
UDYQDQMHLQL]PHQMDYRGLJLWDOQLKVOLNGHO 5HIHUHQþQDYKRGQDPHGLMVNDPHWULND
5*%EDUYQHJDNRGLUDQMDVOLN 5,005*%
Photography and graphic technology - Extended colour encodings for digital image
storage, manipulation and interchange - Part 3: Reference input medium metric RGB
colour image encoding (RIMM RGB)
Photographie et technologie graphique - Codages par couleurs étendues pour stockage,
manipulation et échange d'image numérique - Partie 3: Codage d'image en couleurs
RVB par référence d'entrée par voie métrique
Ta slovenski standard je istoveten z: ISO/TS 22028-3:2006
ICS:
01.070 Barvno kodiranje Colour coding
37.040.99 Drugi standardi v zvezi s Other standards related to
fotografijo photography
37.100.01 *UDILþQDWHKQRORJLMDQD Graphic technology in
VSORãQR general
SIST-TS ISO/TS 22028-3:2011 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST-TS ISO/TS 22028-3:2011
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SIST-TS ISO/TS 22028-3:2011
TECHNICAL ISO/TS
SPECIFICATION 22028-3
First edition
2006-08-15
Photography and graphic technology —
Extended colour encodings for digital
image storage, manipulation and
interchange —
Part 3:
Reference input medium metric RGB
colour image encoding (RIMM RGB)
Photographie et technologie graphique — Codages par couleurs
étendues pour stockage, manipulation et échange d'image
numérique —
Partie 3: Codage d'image en couleurs RVB par référence d'entrée par
voie métrique
Reference number
ISO/TS 22028-3:2006(E)
©
ISO 2006
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SIST-TS ISO/TS 22028-3:2011
ISO/TS 22028-3:2006(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.
© ISO 2006
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
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Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 1
4 Requirements . 5
4.1 General. 5
4.2 Reference viewing environment. 6
4.3 Reference medium primaries and white point. 7
4.4 RIMM RGB colour image encoding. 7
4.5 Inverse RIMM RGB transformation . 11
Annex A (informative) Example colour rendering transform from RIMM RGB to ROMM RGB. 14
Bibliography . 18
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Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
In other circumstances, particularly when there is an urgent market requirement for such documents, a
technical committee may decide to publish other types of normative document:
⎯ an ISO Publicly Available Specification (ISO/PAS) represents an agreement between technical experts in
an ISO working group and is accepted for publication if it is approved by more than 50 % of the members
of the parent committee casting a vote;
⎯ an ISO Technical Specification (ISO/TS) represents an agreement between the members of a technical
committee and is accepted for publication if it is approved by 2/3 of the members of the committee casting
a vote.
An ISO/PAS or ISO/TS is reviewed after three years in order to decide whether it will be confirmed for a
further three years, revised to become an International Standard, or withdrawn. If the ISO/PAS or ISO/TS is
confirmed, it is reviewed again after a further three years, at which time it must either be transformed into an
International Standard or be withdrawn.
ISO/TS 22028-3 was prepared by Technical Committee ISO/TC 42, Photography, in collaboration with
Technical Committee ISO/TC 130, Graphic technology.
ISO 22028 consists of the following parts, under the general title Photography and graphic technology —
Extended colour encodings for digital image storage, manipulation and interchange:
⎯ Part 1: Architecture and requirements
⎯ Part 2: Reference output medium metric RGB colour image encoding (ROMM RGB)
[Technical Specification]
⎯ Part 3: Reference input medium metric RGB colour image encoding (RIMM RGB)
[Technical Specification]
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Introduction
This part of ISO 22028 has been developed in order to meet the industry need for a complete,
fully-documented, publicly-available definition of a wide-primary scene-referred extended colour gamut
red-green-blue (RGB) colour image encoding. This encoding provides a way to represent scene-referred
images that does not limit the colour gamut to those colours capable of being displayed on a CRT monitor, or
require the use of negative RGB colorimetry co-ordinates.
A scene-referred extended colour gamut colour encoding is particularly desirable for professional photography
applications. For example, colours captured by digital cameras, as well as conventional capture devices such
as photographic film, can be outside those that can be represented within the colour gamut of a typical
monitor or other types of output devices. Similarly, scene-referred images can have a larger luminance
dynamic range than output-referred images since they have not been modified by a colour rendering process
to fit the images to a specific output medium applying appropriate tone and colour reproduction aims.
Retaining the unrendered scene-referred image data has the advantage that it preserves the option to make
decisions about how a particular image is to be rendered. For example, a scene-referred image of a backlit
scene can retain information about both the dark foreground region and the bright background region of the
scene. This information can be used to make a properly exposed print of either the foreground region or the
background region, or alternatively can be used to create an improved image by rendering the two regions
differently.
By using a standard scene-referred extended colour gamut colour image encoding, images can be stored,
interchanged and manipulated without restricting the image to a particular rendering intent or output device.
The Reference input medium metric RGB (RIMM RGB) colour encoding specified in this part of ISO 22028
meets the needs of these types of applications. An extended dynamic range version of this colour image
encoding known as Extended reference input medium metric RGB (ERIMM RGB) is also specified for use with
high-dynamic range input sources. (E)RIMM RGB is intended to be a companion to the output-referred ROMM
RGB colour image encoding specified in ISO/TS 22028-2. Both colour encodings are based on the same
“wide RGB” additive colour space to facilitate the development of image processing algorithms and simple
colour rendering transformations to convert scene-referred RIMM RGB images to rendered output-referred
ROMM RGB images.
The International Organization for Standardization (ISO) draws attention to the fact that it is claimed that
compliance with this document may involve the use of patents concerning extended range colour encodings
given in 4.4 and 4.5. ISO takes no position concerning the evidence, validity and scope of this patent right.
The holder of this patent right has assured the ISO that he/she is willing to negotiate licences under
reasonable and non-discriminatory terms and conditions with applicants throughout the world. In this respect,
the statement of the holder of this patent right is registered with ISO. Information may be obtained from
Director, Corporate Commercial Affairs
Eastman Kodak Company
343 State Street
Rochester, New York 14650-0211, U.S.A.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights other than those identified above. ISO shall not be held responsible for identifying any or all such patent
rights.
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TECHNICAL SPECIFICATION ISO/TS 22028-3:2006(E)
Photography and graphic technology — Extended colour
encodings for digital image storage, manipulation and
interchange —
Part 3:
Reference input medium metric RGB colour image encoding
(RIMM RGB)
1 Scope
This part of ISO 22028 specifies a family of scene-referred extended colour gamut RGB colour image
encodings designated as Reference input medium metric RGB (RIMM RGB). Digital images encoded using
RIMM RGB can be manipulated, stored, transmitted, displayed, or printed by digital still picture imaging
systems. Three precision levels are defined using 8-, 12- and 16-bits/channel. An extended luminance
dynamic range version of RIMM RGB is also defined designated as Extended reference input medium metric
RGB (ERIMM RGB). Two precision levels of ERIMM RGB are defined using 12- and 16-bits/channel.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 22028-1:2004, Photography and graphic technology — Extended colour encodings for digital image
storage, manipulation and interchange — Part 1:Architecture and requirements
ISO/CIE 10527:1991, CIE standard colorimetric observers
CIE Publication 15, Colorimetery
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
adapted white
colour stimulus that an observer who is adapted to the viewing environment would judge to be perfectly
achromatic and to have a luminance factor of unity; i.e. absolute colorimetric coordinates that an observer
would consider to be a perfect white diffuser
NOTE The adapted white can vary within a scene.
3.2
additive RGB colour space
colorimetric colour space having three colour primaries (generally red, green and blue) such that CIE XYZ
tristimulus values can be determined from the RGB colour space values by forming a weighted combination of
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the CIE XYZ tristimulus values for the individual colour primaries, where the weights are proportional to the
radiometrically linear colour space values for the corresponding colour primaries
NOTE 1 A simple linear 3 × 3 matrix transformation can be used to transform between CIE XYZ tristimulus values and
the radiometrically linear colour space values for an additive RGB colour space.
NOTE 2 Additive RGB colour spaces are defined by specifying the CIE chromaticity values for a set of additive RGB
primaries and a colour space white point, together with a colour component transfer function.
3.3
colorimetric colour space
colour space having an exact and simple relationship to CIE colorimetric values
NOTE Colorimetric colour spaces include those defined by CIE (e.g. CIE XYZ, CIELAB, CIELUV, etc.), as well as
colour spaces that are simple transformations of those colour spaces (e.g. additive RGB colour spaces).
3.4
colour component transfer function
single variable, monotonic mathematical function applied individually to one or more colour channels of a
colour space
NOTE 1 Colour component transfer functions are frequently used to account for the nonlinear response of a reference
device and/or to improve the visual uniformity of a colour space.
NOTE 2 Generally, colour component transfer functions will be nonlinear functions such as a power-law (i.e. “gamma”)
function or a logarithmic function. However, in some cases a linear colour component transfer function can be used.
3.5
colour encoding
generic term for a quantized digital encoding of a colour space, encompassing both colour space encodings
and colour image encodings
3.6
colour gamut
solid in a colour space, consisting of all those colours that are either: present in a specific scene, artwork,
photograph, photomechanical, or other reproduction; or capable of being created using a particular output
device and/or medium
3.7
colour image encoding
digital encoding of the colour values for a digital image, including the specification of a colour space encoding,
together with any information necessary to properly interpret the colour values such as the image state, the
intended image viewing environment and the reference medium
NOTE 1 In some cases; the intended image viewing environment will be explicitly defined for the colour image
encoding. In other cases, the intended image viewing environment can be specified on an image-by-image basis using
metadata associated with the digital image.
NOTE 2 Some colour image encodings will indicate particular reference medium characteristics, such as a reflection
print with a specified density range. In other cases; the reference medium will be not applicable, such as with a scene-
referred colour image encoding, or will be specified using image metadata.
NOTE 3 Colour image encodings are not limited to pictorial digital images that originate from an original scene, but are
also applicable to digital images with content such as text, line art, vector graphics and other forms of original artwork.
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3.8
colour rendering
mapping of image data representing the colour-space coordinates of the elements of a scene to output-
referred image data representing the colour space coordinates of the elements of a reproduction
NOTE Colour rendering generally consists of one or more of the following:
⎯ compensating for differences in the input and output viewing conditions;
⎯ tone scale and gamut mapping to map the scene colours onto the dynamic range and colour gamut of the
reproduction;
⎯ applying preference adjustments.
3.9
colour space
geometric representation of colours in space, usually of three dimensions
[CIE Publication 17.4:1987, 845-03-25]
3.10
colour space encoding
digital encoding of a colour space, including the specification of a digital encoding method, and a colour space
value range
NOTE Multiple colour space encodings can be defined based on a single colour space where the different colour
space encodings have different digital encoding methods and/or colour space value ranges. (For example, 8-bit sRGB and
10-bit e-sRGB are different colour space encodings based on a particular RGB colour space.)
3.11
colour space white point
colour stimulus to which colour space values are normalized
NOTE It is not necessary that the colour space white point correspond to the assumed adapted white point and/or the
reference medium white point for a colour image encoding.
3.12
continuous colour space values
real-valued, unbounded colour space values that have not been encoded using a digital encoding method
3.13
digital imaging system
system that records and/or produces images using digital data
3.14
extended gamut
colour gamut extending outside that of the standard sRGB CRT display as defined by IEC 61966-2-1
3.15
image state
attribute of a colour image encoding indicating the rendering state of the image data
NOTE The primary image states defined in this document are the scene-referred image state, the original-referred
image state and the output-referred image state.
3.16
luminance factor
ratio of the luminance of the surface element in the given direction to that of a perfect reflecting or transmitting
diffuser identically illuminated
[CIE Publication 17.4:1987, 845-04-69]
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3.17
observer adaptive luminance factor
ratio of the luminance of a stimulus to the luminance of a stimulus that an observer adapted to the viewing
environment would interpret to be a perfect white diffuser
3.18
output-referred image state
image state associated with image data that represents the colour space coordinates of the elements of an
image that has undergone colour rendering appropriate for a specified real or virtual output device and
viewing conditions
NOTE 1 When the phrase “output-referred” is used as a qualifier to an object, it implies that the object is in an output-
referred image state. For example, output-referred image data is image data in an output-referred image state.
NOTE 2 Output referred image data is referred to the specified output device and viewing conditions. A single scene
can be colour rendered to a variety of output-referred representations depending on the anticipated output viewing
conditions, media limitations, and/or artistic intents.
NOTE 3 Output-referred image data can become the starting point for a subsequent reproduction process. For
example, sRGB output-referred image data is frequently considered to be the starting point for the colour re-rendering
performed by a printer designed to receive sRGB image data.
3.19
scene
spectral radiances of a view of the natural world as measured from a specified vantage point in space and at a
specified time
NOTE A scene can correspond to an actual view of the natural world or to a computer-generated virtual scene
simulating such a view.
3.20
scene-referred image state
image state associated with image data that represents estimates of the colour space coordinates of the
elements of a scene
NOTE 1 When the phrase “scene-referred” is used as a qualifier to an object, it implies that the object is in a scene-
referred image state. For example, scene-referred image data is image data in a scene-referred image state.
NOTE 2 Scene-referred image data can be determined from raw DSC image data before colour rendering is performed.
Generally, DSCs do not write scene-referred image data in image files, but some do so in a special mode intended for this
purpose. Typically, DSCs write standard output-referred image data where colour rendering has already been performed.
NOTE 3 Scene-referred image data typically represents relative scene colorimetry estimates. Absolute scene
colorimetry estimates can be calculated using a scaling factor. The scaling factor can be derived from additional
information such as the image OECF, FNumber or ApertureValue, and ExposureTime or ShutterSpeedValue tags.
NOTE 4 Scene-referred image data can contain inaccuracies due to the dynamic range limitations of the capture
device, noise from various sources, quantization, optical blurring and flare that are not corrected for, and colour analysis
errors due to capture device metamerism. In some cases, these sources of inaccuracy can be significant.
NOTE 5 The transformation from raw DSC image data to scene-referred image data depends on the relative adopted
whites selected for the scene and the colour space used to encode the image data. If the chosen scene adopted white is
inappropriate, additional errors will be introduced into the scene-referred image data. These errors can be correctable if
the transformation used to produce the scene-referred image data is known, and the colour encoding used for the
incorrect scene-referred image data has adequate precision and dynamic range.
NOTE 6 The scene can correspond to an actual view of the natural world, or be a computer-generated virtual scene
simulating such a view. It can also correspond to a modified scene determined by applying modifications to an original
scene to produce some different desired scene. Any such scene modifications need to leave the image in a scene-referred
image state, and need to be done in the context of an expected colour rendering transform.
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3.21
tristimulus value
amounts of the three reference colour stimuli, in a given trichromatic system, required to match the colour of
the stimulus considered
[CIE Publication 17.4:1987, 845-03-22]
3.22
veiling glare
light, reflected from an imaging medium, that has not been modulated by the means used to produce the
image
NOTE 1 Veiling glare lightens and reduces the contrast of the darker parts of an image.
NOTE 2 In CIE Publication 122, the veiling glare of a CRT display is referred to as ambient flare.
3.23
viewing flare
veiling glare that is observed in a viewing environment but not accounted for in radiometric measurements
made using a prescribed measurement geometry
NOTE The viewing flare is expressed as a percentage of the luminance of adapted white.
4 Requirements
4.1 General
Reference input medium metric RGB (RIMM RGB) is an extended colour gamut RGB colour image encoding
of the colorimetry of a scene-referred image. The scene-referred image has the intended colour appearance
when viewed in a specified reference viewing environment. The image colorimetry is encoded in terms of an
additive RGB colour space associated with a hypothetical additive colour device having a specified set of
primaries, no cross-talk between the colour channels and a maximum luminance value corresponding to
200 % of a perfect diffuse reflector (i.e. an observer adaptive luminance factor of 2,0).
NOTE 1 Scene-referred image data can correspond to an actual view of the natural world, or a simulation of such a
view. It can also correspond to a modified scene determined by applying modifications to an original scene. For example,
such modifications could include removing haze from the captured image, or allowing a user to manually adjust the
exposure/white balance. It could also include more complex operations such as using a “dodge-and-burn” algorithm to
correct over-exposed regions of a backlit scene. (This can be viewed as being analogous to “re-lighting” the scene.) Scene
modifications could also include applying desired changes to the scene such as simulating a “night” scene, making grass
greener to make it look healthier, or making the sky bluer to make it look clearer. Any such scene modifications need to
leave the image in a scene-referred image state, and need to be done in the context of the expected colour rendering
transform. For example, typical colour rendering transforms will include a boost in the chroma of the image. Any boost in
colourfulness of the scene (e.g. making the grass greener) must be done with the knowledge that there will be an
additional chroma boost during colour rendering. Consequently, the colour rendering transform must be included in any
image preview path that is used to provide subjective feedback to a user during the scene-editing process.
NOTE 2 The image colorimetry of the scene-referred image can contain inaccuracies due to the dynamic range
limitations of the capture device, noise from various sources, quantization, optical blurring and flare that are not corrected
for, and colour analysis errors due to capture device metamerism. In some cases, these sources of inaccuracy can be
significant.
Three different precision levels are defined, and shall be identified as RIMM8 RGB, RIMM12 RGB and
RIMM16 RGB, for 8-, 12- and 16-bits/channel (24-, 36- and 48-bits/pixel) representations, respectively.
Extended reference input medium metric RGB (ERIMM RGB) is an extended luminance dynamic range
version of RIMM RGB having a maximum observer adaptive luminance factor of about 316. Two different
precision levels are defined, and shall be identified as ERIMM12 RGB and ERIMM16 RGB, for 12- and
16-bits/channel (36- and 48-bits/pixel) representations, respectively.
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The image colorimetry shall be based on flareless (or flare corrected) colorimetric measurements as described
in CIE Publication No. 15 using the CIE 1931 standard colorimetric observer defined in ISO/CIE 10527.
When digital images are interchanged in an open systems environment using the RIMM RGB or ERIMM RGB
colour encodings, a default colour rendering function or a full resolution standard output-referred image should
be associated with the RIMM RGB or ERIMM RGB image data in order to unambiguously define baseline
colour rendering aims for the image, and allow the image to be used in applications which do not directly
support the usage of scene-referred image data. Furthermore, in an open systems environment, the RIMM
RGB or ERIMM RGB image data should be exchanged using a file format which requires the file reader to
apply the default colour rendering function or use the standard output-referred image data as the image data
to be conveyed, unless the RIMM RGB or ERIMM RGB image data is specifically requested by the application.
NOTE 3 The JPEG 2000 file format provides a mechanism for storing images in RIMM RGB or ERIMM RGB and
specifying baseline colour rendering aims through the use of the Restricted ICC Profile method.
NOTE 4 In some cases, it can be desirable for a user or an application to override the provided baseline colour
rendering aims in order to specify custom colour rendering aims for an image.
The colour image encoding defined in this Technical Specification conforms to the requirements defined in
Clause 5 of ISO 22028-1:2004.
4.2 Reference viewing environment
The reference viewing environment shall be such that the adapted white has the chromaticity values of
CIE Standard Illuminant D (x = 0,345 7, y = 0,358 5).
50 0 0
The absol
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